Telecommunication channels are used to deliver various types of signals, including, data, audio and video signals, which are provided in what is generally referred to as communication connections. Each channel has a capacity which is the amount of data it can carry during a given period. A service resource monitor (SRM) generally determines which connections are admitted to the channel, in a manner which prevents overloading of the channel. This task is relatively easy when dealing with connections which have a fixed bit rate. But when a connection has a variable bit rate (VBR), the admission task becomes more complex. To ensure that all data is transmitted to its intended recipient, it is possible to allocate to each connection a bandwidth amount required for its largest data throughput over time, but such an allocation may be very wasteful. Accordingly, there have been suggestions to use statistical measures for voice connections which do not vary substantially over time. One such suggestion for voice calls appears in U.S. Pat. No. 7,369,490 to Azami et al., titled: “Method and Apparatus for Call Event Processing in a Multiple Processor Call Processing System”, the disclosure of which is incorporated herein by reference.
The handling of VBR video is traditionally more complex than handling varying audio signals and therefore nearly all implemented video communication systems use constant bit rate (CBR) video streams. It is noted, however, that for a given quality level, some video frames, such as those having a large amount of detail, can be compressed only to a small extent, while other video frames (e.g., frames merely showing a blue sky) can be compressed to a larger extent. Therefore, many video compression methods provide variable bit-rate (VBR) video streams, in which different frames are compressed by different amounts.
US patent publication 2006/0182027 to Conte et al., titled: “Method and Apparatus for Controlling Data Flows in Telecommunications Network”, the disclosure of which is incorporated herein by reference, describes a measure for representing the size of video streams, for use in admission decisions.
U.S. Pat. No. 6,269,078 to Lakshman et al., titled: “Method and Apparatus for supporting Compressed Video with Explicit Rate Congestion Control”, the disclosure of which is incorporated herein by reference, describes a method of delivering video and allocation of bandwidth.
U.S. Pat. No. 7,149,185 to Suni, titled: “Measurement based connection Admission Control (MBAC) Device for a Packet Data Network”, the disclosure of which is incorporated herein by reference, describes an admission method based on an estimation of an envelope of the video stream, for an asynchronous transfer mode (ATM) network.
U.S. Pat. No. 5,335,222 to Kamoi et al., titled: “Traffic Control System for Asynchronous Transfer Mode Exchange”, the disclosure of which is incorporated herein by reference, describes another admission method.
PCT publication WO 00/38378 to Meyer et al., titled: Admission Control of Mixed VBR Sources in Broadband Networks”, the disclosure of which is incorporated herein by reference, describes another admission method for VBR traffic.
U.S. Pat. No. 5,848,057 to Lee et al., titled: “Apparatus for Estimating Variable Bit Rate (VBR) Video Traffic, and Method Therefor”, the disclosure of which is incorporated herein by reference, describes another bandwidth estimation method.
The methods described in the above references are generally either relatively complex or do not provide sufficient bandwidth utilization efficiency.